ACTA issues

Invertibility conditions and bounds for spectra of operator matrices

M. I. Gil'

Acta Sci. Math. (Szeged) 67:1-2(2001), 299-314

Abstract. Operator matrices in Banach and Hilbert spaces are considered. Invertibility conditions and bounds for the spectrum are established. Besides, the Gershgorin types bounds are improved for operator matrices, which are close to triangular ones. An application to matrix differential operators is discussed.

AMS Subject Classification (1991): 47A10, 47A55

Keyword(s): operator matrices, invertibility conditions, spectrum perturbations, differential operators

Received June 14, 1999. (Registered under 2785/2009.)